1. Department of Orthopedics; Medical Faculty; University Düsseldorf; Düsseldorf Germany
2. Department of Diagnostic and Interventional Radiology; Medical Faculty; University Düsseldorf; Düsseldorf Germany
3. Center for Hip Preservation and Children's Orthopedics; San Diego California
4. Hosalkar Institute for Joint Preservation and Injury Care; San Diego California
5. Department of Pathology, Medical Faculty; University Düsseldorf; Düsseldorf Germany